The good:
- Amateur & Pro features for a song
- Boss mode is kinda fun
- More songs
- Achievements (i guess)

The bad:
- The "disappearing arrows" effect when you hit a note is very distracting. I know you can turn it off, but that gives just less feedback (preferred the rings from SCGMD3")
- The guitarist visuals are also very distracting.
- No "plunk" sound when you make a mistake.